1. Technical Field
Embodiments of the present disclosure generally relate to a sense amplifier of a semiconductor device, and more particularly to a sense-amplifier layout structure.
2. Related Art
A semiconductor memory device includes a sense-amplifier circuit configured to sense and amplify data stored in a memory cell, and output the amplified data.
The sensing method of a general bit line sense amplifier uses a differential pair sensing method, and the most popular sense amplifier is a cross-coupled latch sense amplifier.
FIG. 1 is a circuit diagram illustrating a general cross-coupled latch sense amplifier corresponding to a folded bit line structure.
In FIG. 1, the sense amplifier consists of: a bit line sense amplifier 2 configured to operate by power-supply signals (SAP, SAN) as well as to sense and amplify a signal difference between bit lines (BL, /BL); a precharge unit 4 enabled by a precharge signal (BLEQ) being output when the sense amplifier does not operate, so as to precharge the pair of bit lines (BL, /BL) with a precharge voltage (VBLP); an equivalent unit 6 enabled by the precharge signal (BLEQ) such that voltage levels of the bit lines (BL, /BL) are identical to each other; and a data output unit 8 configured to output a data signal amplified by the bit line sense amplifier to segment input/output (I/O) lines (SIO, SIOB) according to a column control signal (Yi). The signals of the segment I/O lines (SIO, SIOB) may be amplified by a local sense amplifier (LSA) (not illustrated) and then output to local I/O lines.
FIG. 1 is a circuit diagram of the sense amplifier 1.
Although the data output unit 8 of the sense amplifier 1 consists of at least one NMOS transistor, many developers and companies are conducting intensive research into methods for replacing the NMOS transistor of the data output unit 8 with at least one PMOS transistor to improve write time (tWR) deterioration characteristics.
However, assuming that the transistor of the data output unit 8 is implemented as the PMOS transistor, the region occupied by the sense amplifier unavoidably increases in size due to the characteristics of a PMOS transistor.